Solid ink or phase change ink printers conventionally receive ink in various solid forms, such as pellets or ink sticks. The solid ink pellets or ink sticks are typically inserted through an insertion opening of an ink loader for the printer, and the ink sticks are moved along a feed channel by a feed mechanism and/or gravity toward a melting device. The melting device heats the solid ink impinging on the device until it melts. The liquid ink is collected and delivered to a printhead for jetting onto a recording medium.
Known ink sticks are variously configured with predetermined protuberances and indentations that serve a number of purposes. Some previously known solid ink stick configurations included protuberances and indentations that restrict the insertion of solid ink sticks into particular feed channel openings. In other configurations, some of the protuberances and indentations are used to guide the ink stick through a feed channel, to limit the interaction of the ink stick with feed channel structures, to interact with identification sensors within the ink loading device, or to activate sensors positioned along the feed channel to provide information regarding the position of the ink stick in a feed channel. Other protuberances and indentations provide humanly perceptible indicia that help a user identify an ink stick color or help a user correlate an ink stick with a particular printer or feed channel in a printer. In each ink stick configuration, a balance is required between ink stick esthetics, unique identification and intended usage purposes for different printer configurations and ink formulations, and the need to provide a customer with a reasonable volume of ink that will withstand manual handling and maneuvering along a feed channel to a melting device. Each configuration requires thorough and careful engineering.